Patent GB-968897-A (GB)
Title: Improvements in or relating to disc brakes
Inventor: RODWAY JOHN
IPC: F16D55/2255
Filed: 1961-11-08
Abstract: 968,897. Disc brakes. AUTOMOTIVE PRODUCTS CO. Ltd. Nov. 8, 1962 [Nov. 8, 1961; Nov. 10, 1961; Dec. 19, 1961], Nos. 40049/61, 40368/61 and 45498/61. Heading F2E. In a disc brake of the kind having a slidably or pivotally mounted member and associated pads on opposite sides of a disc, one of which is applied directly by the piston of a fluid pressure cylinder mounted on the member and the other by the reaction in the cylinder acting through the member, alternative manual applying means comprises a lever movable in a plane normal to the axis of the cylinder and a ball and inclined recess cam device whereby movement of the lever applies the one pad directly via an automatic adjustment device located in or around the cylinder. In one embodiment, Figs. 1 and 3, the member 23 is of closed loop formation and is located on a support 26 for sliding movement transversely of the plane of a disc 20. Pads 21, 22 are respectively carried by backing plates 29, 31 which are shaped to provide shoulders, the shoulders of plate 29 resting on edges of the opening in member 23 while those of plate 31 rest on the support 26 adjacent downturned portions 28 which prevent circumferential movement of pad 22 and guide the latter for axial movement. Split pins 33 inserted through a bracket 34 on member 23 and flanges 35 on a cylinder 24 secured to the member 23 normally prevent radial movement of the pads and are removable to facilitate pad replacement. A spring clip 36 and spring 37 maintain sliding contact between member 23 and support 26 and prevent vibration. Cylinder 24 contains a piston 25 acting directly on backing plate 31, the reaction acting via the member 23 on the backing plate 29 so that on supply of fluid to the cylinder both pads are applied. The alternative manual applying means and automatic clearance adjuster comprises a manually moved lever 47 mounted on a pin 46 integral with a ratchet wheel 43 in turn connected by a splined connection 44a to a thrust member composed of two parts 43, 42 in screw-threaded engagement with one another, the part 42 being secured non-rotatably to the piston. A pawl 52 engaging the ratchet wheel is secured to the lever 47 and a holding pawl 53 is secured to member 23. When lever 47 is moved from its rest position balls 50 ride up sloping faces of recesses 48 and 49 in the lever and member 23 respectively so that lever 47 acts via balls 51 on the ratchet wheel and thrust member assembly to move piston 25 to apply the brake. If the movement of lever 47 is excessive pawl 52 slips over a tooth of the ratchet wheel so that on subsequent brake release movment of lever 47 ratchet wheel 44 is rotated by pawl 52 in a direction to increase the length of the thrust member. In a second embodiment, Fig. 5, the member 23 is pivoted at 55 to a support 56, the member 23 and support 56 supporting and guiding the shoes 21, 22 as in the previous embodiment. The manual applying means is also as in the previous embodiment except that the ratchet wheel is formed integrally with the thrust member, consisting of teeth 62 formed on part 59 of the thrust member and co-operating with a pawl 71 on lever 64 and holding pawl 72. In a third embodiment, Fig. 9, the cylinder 24 is annular and contains an annular piston 25 sealed externally by a gland 88 and in the centre by a seal 87 attached to end 85 of a thrust member formed of parts 78, 81, manual operation and automatic adjustment of which are effected as in the first two embodiments. In a fourth embodiment, Fig. 10, manually operated lever 101 is formed with a ring 102 surrounding the cylinder and rotatable upon movement of the lever to cause balls 104 to rise up the sides of recesses 103, 105 in the ring and a thrust ring 106, respectively, the latter being secured to the backing plate of the pad applied by the piston. The reaction force on the ring 102 is taken by a ring 99 threaded on the cylinder and having ratchet teeth 108 engaged by a pawl 107 carried by ring 102 so that automatic adjustment is effected as in the previous embodiments. A holding pawl, not shown, is also provided. In a fifth embodiment (Fig. 12, not shown) the previous construction is modified in that a ball race is positioned between the ring on the applying lever and the ring having the ratchet teeth, to reduce friction. In a further embodiment, Fig. 13, a manually operated lever 134 is formed with a rotatable ring 133 mounted, together with a non-rotatable ring 128, on part 126 of a thrust member 125, 126 arranged between piston 25 and the backing plate of pad 22. Rings 128, 133 have complementary undulating grooves 131, 132 between which are located balls 135 by which, upon movement of the lever, thrust is applied between the cylinder 24 and pad 22. Pawls 136, 137, respectively on ring 133 and the cylinder co-operate with ratchet teeth formed on the part 126 to effect automatic adjustment of the thrust member which is thereby effective for both manual and power operation.